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Aged meat has been in demand because consumers seek out more natural and minimally processed meats. It is a natural value-adding process that improves the sensory attributes of meat and increases its tenderness, juiciness, and flavor. Essentially, in the absence of microbial spoilage, holding the unprocessed meat above its freezing point is known as "ageing." It is also referred to as conditioning, tenderizing, ripening, or maturing meat. In this process, the action of enzymes in the meat plays a key role, while bacterial action is not of much importance. Lamb meat is not affected by age because it is slaughtered while it is still developing tenderness. There are two types of aging practiced commercially: dry and wet aging.
• Dry ageing:
Dry aging is the traditional process of placing an entire carcass or wholesale cut in a refrigerator for 21 to 28 days. The required temperature is 32–34 degrees Fahrenheit, with a relative humidity of 100-85 percent and an air velocity of 0.5-2.5 meters per second. Care should be taken to maintain the exact temperature and humidity conditions since too much humidity can cause excessive microbial growth whereas too little will cause excessive shrinkage. 85 percentage relative humidity is the happy medium in slowing microbial growth and moisture loss. Tenderness development can be accelerated by aging at higher temperature and air velocity acts as the medium for moisture removal from the refrigerated area. Insufficient air velocity will cause excessive moisture to condense on the product and affects the flavour and aromas of the meat. On the other hand, too high air velocity will allow excessive surface drying and results in weight and trim losses. This above-mentioned condition, that is, the cost associated with the weight and trim losses is the main disadvantage of dry aging. It is the predominant method of post-mortem aging today since most meats are vacuum packaged at the site of carcass fabrication or cutting. Final meat product has a brown-roasted, almost meaty flavor.
• Wet aging:
Wet aging is the process of aging meats in vacuum bags under refrigeration at 32–34 degrees Fahrenheit. The main distinction between wet and dry aging is that humidity and air velocity are not required. The aging process continues when a primal or subprimal cut has been placed in a vacuum package. Meats generated by wet aging have a more bloody or serum-like, and metallic flavor.
It is clear that the conversion of muscle to meat causes significant changes in its flavor and quality. In the conversion process, natural enzymes found in muscles break down specific proteins in muscle fibers. This breaking of protein strands is called myofibrils, and it results in improved tenderness. The three main changes that occur are protein denaturation, proteolysis, and flavor enhancement.
1. Protein Denaturation:
The physical rearrangement of chemical bonds in amino acids of a protein polypeptide chain that does not involve hydrolysis is referred to as denaturation. During post-mortem, sarcoplasmic proteins denature to a varying degree. It enhances tenderness but also leads to a loss of the water-holding capacity of muscle protein.
2. Proteolysis:
During aging, the sarcoplasmic reticulum loses its capacity to retain calcium ions, and its release initiates a water-soluble enzyme called "Calcium-Activated Sarcoplasmic Factor." This factor degrades many proteins, like M-line protein, causing tenderization of meat. They also degrade the cross-links of non-helical telopeptides of collagen. As a result of proteolysis, water holding capacity improves.
3. Flavour Enhancement:
During aging, ATP is broken down into mononucleotides (AMP and IMP), which produce inosinic acid and hypoxanthine, enhancing the flavor of meat. The Milliard reaction is a type of reaction that takes place in the later stages of aging due to the breakdown of proteins and the accumulation of free amino acids. It is a non-enzyme reaction that can form brown compounds that may cause discoloration and impart a bitter taste to meats.
Discoveries in food have opened up new possibilities and methods to preserve food in the best way possible. So have a go at aging your meats, and who knows, you might come up with something innovative and, most importantly, delicious!
